The door at the back of a Wilmette movie house cracked open. A young girl poked her head in. She spotted a half dozen or so twentysomethings standing amid the seats of an otherwise empty theater and her eyes grew wide. “Wow! Hey! Team StarKid!” she shouted, and the young theater troupe/Internet sensation/fledgling multi-platform entertainment juggernaut known as Team StarKid collectively turned. Embarrassed, the girl pulled her head out and the door banged shut. Team StarKid waved then turned back to talking about their friends and auditions and day jobs, their recent move to Chicago, whether their cars were being towed out front and how their latest soundtrack was doing on iTunes.

Turns out, on this Saturday last spring, it was doing pretty well. “We just passed the ‘Glee’ soundtrack,” someone said.

A letter was opened; a fan had just pressed it into the hands of a StarKid. It read: "I want to thank you. You guys are the reason I want to change what I want to do." The StarKids let out an "Awww!" Although they are getting used to it. In fact, Team StarKid had to be herded here, into one of two movie houses in the Wilmette Theatre, so they could stay out of sight of fans, hyperventilating with anticipation in the adjacent theater.

Wait, what is Team StarKid?

Depending on whom you ask, they are the future of musical theater, the future of theater marketing or simply the future — a quasi-theater company that sings, dances, jokes, emotes and has built a considerable following entirely through social networking websites and word of mouth. Pat Brady, their Los Angeles-based agent, when talking with old-school media types, tends to refer to them as "a new media theater production company."

So why haven't I heard of them?

Because if you have to ask who or what Team Starkid is, you are, like, so old. Like, 26 or something.

In which case, Team StarKid would probably look like struggling college graduates, fresh out of school. Which they are, with a couple of differences: They have a large following. And serious prospects. A couple of years ago, the members of Team StarKid were theater majors at the University of Michigan at Ann Arbor, where they staged a small, satiric adaptation of the Harry Potter series they called "A Very Potter Musical." It cost them $1,000. Video footage from the show was posted online, and "A Very Potter Musical" began circulating within Harry Potter fandom.

This led to Darren Criss, a founding member (and their Harry), getting cast on "Glee" and becoming a star. It also led to more StarKid productions, including "A Very Potter Sequel" in 2010. Which led to most of Team StarKid settling on Chicago as a home base, working on even more shows and developing a consistent and clever, wide-eyed, pop-culture-scrounging musical theater sensibility. Which led to the self-produced soundtrack for its most recent musical, "Starship," going to No. 1 on the iTunes music charts. Which now has led to a sold-out concert tour featuring the same songs, starting Friday in Ann Arbor. (The Tuesday show at the Bottom Lounge is sold out.)

All of which, as of last week, has led to videos of StarKid's productions being watched 100 million times.

How promising is StarKid?

So promising the Wilmette Theatre event was actually a screening of a video of last winter's Chicago production of "Starship" at the Hoover-Leppen Theatre on Halsted Street — all 3 1/2 hours of it. It's a video so flatly produced it could have been shot by a parent with a camcorder. And yet, the screening was sold out.

How did I miss this?

Ask yourself: Am I 14? Female? Obsessed with Harry Potter?

If not, your ignorance is understandable. As Brian Holden, one of the founding members, told Variety, "Our marketing team is Twitter and teenage girls telling their friends." On the other hand, StarKid's unwillingness to settle on a traditional media model has been confusing — when I asked the StarKids what they were, I got everything from "comedy troupe" to "online repertory theater company." Even Criss, speaking by phone from Los Angeles, said, "I am always explaining StarKid. 'We're under the radar but not really,' or, 'If you're online, then you get us.' Having to explain it is a nightmare in Los Angeles. People are like, 'Wait, you did this in school?' I'm like, 'Yeah, but it's online.' It's so convoluted it always comes down to a pat on my head and this feeling that there is no way at the moment for us to prove our success if you're outside the circle."

Indeed, at Comic Con International in San Diego last summer, during the "Glee" panel, Criss began fielding "question after question about StarKid," remembers StarKid Joey Richter. "So many that the older people on the panel were like, 'Why do they keep asking about this thing?' They didn't seem to know what it was."

Not that it has scared anyone off.

Said Kevin Morrow, president of Live Nation New York: "Personally, I think these kids can choose what they want to do. If they plop down in a theater space, they could. Or they could easily be a TV show. But I think the smart ones want to do it all, and they will." Said Craig Plestis, president of Smart Dog Media, which develops shows for NBC and cable networks (and has been talking to StarKid about a possible variety show): "Something's going on here. They've touched some nerve. They're just not on everyone's radar yet."

A wink away from parody

Six months after that screening, and less than two weeks before opening night of their tour, the StarKids shiver in the drafty audition space they've been renting for weeks above the Strawdog Theatre Company in Lakeview, running through songs for the tour — a kind of greatest-hits package. StarKid Jaime Lyn Beatty wears mittens, StarKid Meredith Stepien wears a coat and director Julia Albain is bundled in a scarf. The room resembles the set of "Rent," cluttered and randomly decorated.

Heat is nonexistent. StarKid Joe Walker explains to StarKid Dylan Saunders what to do if he forgets a lyric. "Point the microphone at the audience. They'll sing it all back," Walker says. Saunders nods.

He knows.

A young two-piece band (just drums and keyboards) slides into spacey opening music and the cast members step onto their imaginary stage, lined up one behind the other, moving in slow, exaggerated strides as if they were malfunctioning robots or walking on the moon. When they reach their microphone stands, the StarKids turn their backs to their imaginary audience. Then Richter pivots around and pleads out the opening lines: "I want to be a Starship Ranger/I wanna have the things they've got."

Arms and hips stay in sync, and as each StarKid spins around and sings a lyric, it's easier to imagine 'N Sync or the Osmonds than the cast of, say, "Rent." Richter, in particular, with thick Muppet eyebrows and puppy dog eyes, looks as if he's channeling decades of pop idols. My brain starts to assign pithy personalities: Richter's the sensitive one; Stepien's the goof; Walker's the lady's man; Saunders is the regular schmo; Beatty's the sad-eyed cynic; Holden's the nerdy one; and choreographer Lauren Lopez is the spunky one.

Fans say the same things again and again about StarKid. As 16-year-old Allegra Rosenberg, of Skokie, put it: "It's so low-fi, it's like something I could do, with a pop lexicon to dig into." Or as a girl from Lincolnshire explained earnestly: "I like (that) they're not corporate sellouts." Meaning, the StarKid sensibility is inside-jokey, knowingly amateurish, opaquely subversive, Up With People with irony, "Rocky Horror Picture Show" without sleaze. A mishmash of pop benchmarks, not great theater. Think "The Little Mermaid," not O'Neill. "This is the result of us being children of the Disney renaissance," Criss said. "And contemporary Broadway musicals."

A lot of StarKid songs celebrate friendship and the collective good, and yet are so overtly broad that everything always seems a wink away from being a parody of such sunshiny good spirits. At the University of Michigan, "the StarKids came off very Judy Garland-Mickey Rooney-'Let's put on a show' to me," says Philip Kerr, one of their theater professors. "But also a few steps ahead even then of where a young theater company might be because they were so smart about using the information age to reach the right audiences."

Indeed, before the last StarKid graduated in May, Kerr says the theater department was already receiving mail from all over the world addressed to them; John Neville-Andrews, the department's head of performance, says the university has even begun to routinely mention Team StarKid as a recruitment tool.

Indeed, a week after graduation, Criss signed with the CESD talent agency. When he mentioned his friends, Brady decided to represent the group. "But I sat them down and said, 'This is wonderful and creative, but the irony to what you do here is that if you don't take the Harry Potter thing down a notch, Warner Bros., which has the film and merchandise rights, are going to own your firstborn,'" he recalls. "So Brian posted an apology online, and the next day Darren got a call. They showed respect for the (Harry Potter) property, and it helped.

"The catch is, they can't make money from the thing they're most famous for. That's the deal."

The other setback is that they don't get much time with Criss now, though he remains involved creatively. After scattering around the country post-graduation, StarKid decided it needed a nonthreatening, central location to work on new material. "I think the feeling was we don't know what the goal is but we like being together, which is not a business plan but it is something worth holding on to," Walker says. Criss remained in LA and wrote "Starship" in his trailer on the set of "Glee"; nearly everyone else came to Chicago.

When they arrived, they sent letters of introduction to the major theater companies to endear themselves to the community. Says Bob Mason, casting director of Chicago Shakespeare Theater, one of those who received their letter: "Chicago is a great place to start a theater company, but I wasn't sure what to make of them. Then their first show was so long. What kind of message is that to send? Not being certain of who they are may be a strong point. But it also sounds like energy shooting all over the place."

"Starship," their Chicago stage debut, opened in February with a dozen performances. Every one sold out. But three-plus hours of light musical sci-fi and references to "Alien" and "Starship Troopers" can be taxing on all but the hopelessly devoted, and the reviews were generally negative. Says Adam Belcuore, casting director for the Goodman Theatre: "I thought, 'They haven't grown into their ability to create a full theatrical evening yet. They also need an editor.' But it was thrilling to be in a room with kids screaming for theater."

Growing from small beans

On the other hand, during the past year, Team StarKid has been called to countless meetings with major theater producers in New York and record labels in Los Angeles. Holden admits "it's tough imagining a partnership (with a media conglomerate) because we want to be undefined as long as possible." When you've already produced yourself to No. 1 on iTunes, it's hard to say what a label can offer. Those meetings, though, Brady says, were often landed for one reason: Some executive has a young daughter.

But no one's making serious cash on this yet. Of the 20 or so members of StarKid, eight work full time for StarKid Productions, which Criss, Holden and classmates Nick and Matt Lang founded after college. "'Starship' soundtrack and T-shirt sales, that's what supports them," their agent says. "Though every single day I get emails from schools and theater groups that want to do 'Potter Musical.' And every single day I have to turn down every one of them, because if they sell one ticket under that name, it would come back and bite us."

What doesn't go into salary goes into producing new shows. And so the other StarKids are employed throughout Chicago as waiters, tour guides and even nannies to the very kids who adore them as StarKids. Some have landed commercials; others audition constantly. Stepien occasionally does stand-up comedy.

Their 21-city tour, like a lot of StarKid happenings, came together quickly. Last summer, they tentatively asked fans on Facebook where they should play if, you know, they ever toured. In September, Saunders met with Steve Gaber, who books tours for Live Nation. "We had the concept, the cities, everything in three weeks," Gaber says. Most of the dates sold out within a few days of going on sale; two shows at the 1,200-seat Irving Plaza in New York sold out in a minute. "We could have done more — they could have played the Chicago Theatre — but we didn't want to go crazy. They haven't toured yet, and it's better to underplay first."

After the tour?

In January, ironically enough, Criss will star on Broadway in "How to Succeed in Business Without Really Trying," replacing Harry Potter himself, Daniel Radcliffe. As for the rest of the group, plans are vague, but vast — maybe a show about the U.S. Constitution, maybe another Harry Potter musical, maybe an animated series or a variety show, or starting a theater company in Chicago, or revisiting (and revamping) "Starship." Holden said two new stage shows have already been written and are ready to be produced.

All of which, if you watch StarKid's no-budget YouTube clips, sounds like a leap. Criss himself admits the group was horrified by the quality of the lighting and sound when the videos went viral. In person, however, in the company of StarKids, you want to drink their Kool-Aid. It's no great exaggeration to say they look like stars. Even Gaber sees himself "down the road, talking about when these guys were gathered in one place."

Because what they offer is compelling: a vision of friends marching arm in arm into a digital future. Still new to Chicago, they generally stick together. They hold movie nights. A dozen or so recently rented a cabin on Lake Erie and spent the weekend telling ghost stories. They regularly patch in Criss and Richter (who live together in Los Angeles) via Skype. "It's not a cult," Beatty says. "If nothing else, it's von Trapp-ish." Or as Criss, who will appear at only one or two of the StarKid tour stops, puts it, "I think we are desperate to hold on to that idea that we are just kids having fun, growing from whatever small beans we've been handed."

Which, in that Lakeview rehearsal space, seems much more realistic than it sounds. "So should we, like, stand in a cluster now," Holden asks Albain, "like we're pretending to decide who's going to sing next?"

"You want to fake a huddle?" she asks.

And so the StarKids form a circle, squash their shoulders together and lean forward with one motion, as though they've been fake-huddling all their lives. Loud stage whispers chime out from inside the scrum:

"But Darren's not here!"

"Who's going to sing?"

"Who'll take his part?"

Before they can fake-decide, Walker breaks through the huddle and pretend-pushes aside his fellow StarKids and ignores their cartoonish glares of outrage and moves downstage and sings, his hand intensely gripping his invisible microphone, his face contorted with fake emotion. Albain shouts an exaggerated, stadium-esque roar of approval. Then Team StarKid spreads out, working the invisible crowd at the lip of the invisible stage — everyone so lacking in self-consciousness despite the corniness and comfortable despite the rough edges, I found myself hoping they wouldn't sand down the rough patches. They are what makes Team StarKid infectious and relatable, especially here, in this cold Chicago attic. Because anyone can put on a show. But only these kids put on this one.

"To be honest," said a mother who had driven to Chicago from Michigan, just so her daughter could attend the screening of a Team StarKid stage production -- a video of a production, mind you, not the thing itself -- "it kind of reminds me of those shows they put on at Disney World. You know, with...